+1 to much of the common sense in Chaals's post, the logic of which
could be applied to other aspects of our work when we appraise the value
of any attribute or element and assess how effective it is.
Also I wish to add that the notion of success or failure is largely
subjective and often difficult to truly assess - so we should be mindful
of that when crunching the numbers in the wild. A small success is still
a success.
Cheers
Josh